JP2023066408A - Bevel tip expandable mouth catheter with reinforcing ring - Google Patents

Abstract

To provide a retrieval catheter with an expandable distal end capable of retrieving an object.SOLUTION: A clot retrieval catheter 100 includes a large bore shaft and a distal braid-supported tip that is expandable to a diameter larger than the outer sheath. A distal mouth 218 of the tip can be beveled at an angle inclined from the longitudinal axis 111 of a shaft 110. The braided tip can be reinforced with a reinforcing ring 211 which can be welded or overmolded to the distal end 214 of the braid and prevents the tip from collapsing under aspiration forces. The reinforcing ring can have relief features 224 positioned to allow the oblique orientation of the ring to maintain a circular inner channel when the tip is compressed and delivered through a guide sheath and expanded at a target site. The distal tip can be expanded to a profile that is either symmetric or asymmetric with the catheter shaft.SELECTED DRAWING: Figure 1

Description

The present invention relates generally to devices and methods for clearing acute occlusions from blood vessels during intravascular medical procedures. More specifically, the present invention relates to a retrieval catheter having an expandable tip capable of retrieving an object or objects.

Clot retrieval aspiration catheters and devices are often used for mechanical thrombosis for endovascular intervention when patients suffer conditions such as acute ischemic stroke (AIS), myocardial infarction (MI), and pulmonary embolism (PE). Used for ablation. Access to the neurovascular bed, in particular, is difficult with conventional techniques due to the small diameter of the target vessel, its long distance to the insertion site, and its high tortuousness. These catheters are often long and must follow the vessel's configuration with all branches and bends. Conventional devices often have too large a profile, lack the deliverability and flexibility needed to navigate particularly tortuous vessels, or dislodge clots when delivered to the target site. is either not valid for

Many existing designs for aspiration and retrieval catheters, for example, are often limited to an inner diameter of 6 Fr, or approximately 0.068-0.074 inches. Larger sizes require the use of a larger guide or sheath, followed by the closure of a larger femoral access hole. Most physicians prefer to use the 8Fr guide/6Fr sheath combination, and few can easily perform more than a 9Fr guide/7Fr sheath combination. This means that once the target site is reached, the size of the clot is often larger than the inner diameter of the aspiration catheter and must be immediately compressed to otherwise enter the catheter port. This compression can cause bunching up during retrieval and subsequent shearing of the clot. Tight, fibrin-rich clots can also clog the fixed port tips of these catheters, making them more difficult to extract. This clogging can also cause shear where the softer portion tears away from the stiffer region of the clot.

The small diameter and fixed tip size are also ineffective in inducing the suction required to remove blood and thrombus material during the procedure. The aspiration must be strong enough so that any fragments that may result from aspiration or use of a mechanical thrombectomy device cannot migrate and occlude the distal vessel. When aspirating with a fixed mouth catheter, a significant portion of the aspiration flow will come from the vascular fluid proximal to the tip of the catheter where there is no clot. This significantly reduces aspiration efficiency and reduces the success rate of clot removal.

Therefore, large bore intermediate and aspiration catheters and/or those with expandable tips are desirable because they provide a large lumen and distal port to receive clots with minimal resistance. The bore lumen of these catheters can be about the same size as the guide and/or sheath through which they are delivered, and the expandable tip can still expand to a larger diameter. . Once a clot is captured and drawn proximally into the funnel-shaped tip, the clot can be gradually compressed during retrieval so that it can be completely aspirated through the catheter and into the syringe or canister.

In many instances, fixed mouth catheters and those with expandable tips can have an underlying braid as the primary scaffold. The use of braids in catheter supports is not a new concept and typical examples can be readily found in the art. The braid can often be simple as a helically wound band in one direction for the length of the catheter, which crosses above and below the helically wound band in the opposite direction. . The band can be metal, fiberglass, or other material that provides effective hoop strength to reinforce the softer outer material of the body. However, support braids also have very high cross-sectional stiffness, either failing to meet the standards of flexibility required in many procedures, or sufficiently for use in fragile vessels without causing substantial trauma. cannot be flexible. Conversely, if many braids have low cross-sectional stiffness and hoop strength, this means that during an aspiration procedure, the applied suction may collapse the tip prior to clot attachment.

Further, advances in catheters provide evidence that increasing the tip surface area of an aspiration catheter can improve aspiration efficiency and enhance the interface with the thrombus. A design with an angled beveled tip has been shown to improve interaction with a clogged clot because it provides more mouth area for aspiration and ingestion than a flat tip. An in vitro study by Vargas et al. demonstrated an approximately 70% improvement in the incidence of complete clot uptake when using a beveled tip catheter compared to a flat tip control device (Varga et al., Journal of Neuro Interventional Surgery 2021; 13:823-826). Therefore, the beveled tip reduces the total number of aspirations for a successful procedure, reduces the additional complications associated with the use of a stentreaver, and/or allows TICI 2C vessels to be treated more frequently with lower mRS scores. May lead to recanalization grade. Nevertheless, due to the reduced hoop stiffness due to the annular bevel geometry compared to a right cylinder, more support may be required to prevent the tip from collapsing.

As a result, it must be sufficiently conformable to easily advance through the guide or sheath in its collapsed state, while being strong enough to withstand suction forces without collapsing. Reconciling these needs without significant trade-offs is difficult.

There remains a need for improved catheter designs that attempt to overcome these design challenges. The design of the present disclosure provides devices and methods that can address the above deficiencies.

It is the purpose of this design to provide a device and method that meets the above needs. Designs are from the cerebral arteries of patients with AIS, from the natural coronary or graft vessels of patients with MI, from the pulmonary arteries of patients with PE, or from other peripheral arteries and veins where clots are causing occlusion. , to a clot retrieval catheter capable of removing clots. The design also addresses the challenge of aspirating clot material by utilizing an expandable tip capable of the aspiration energy/work required to deform these clots, while having a structure that resists collapsing during the procedure. can be resolved.

In some examples, a catheter can have a proximal elongated shaft having a proximal end, a distal end, a large internal bore, and a longitudinal axis extending therethrough. The elongated shaft may have a shaft braid configured around a low friction inner liner. The braid can serve as a backbone and support for the catheter shaft. The interlacing weave of the braid can be of any number of materials or patterns known in the art and can have varying densities and compositions along the length of the shaft.

In many examples, the catheter can have an expandable distal tip section extending from the distal end of the elongated shaft. The tip section can have a collapsed delivery configuration and an expanded deployment configuration. The tip can be radially collapsed for delivery through the outer guide sheath and can assume a funnel-shaped profile in the expanded configuration. The tip may have an outer polymeric membrane or jacket supported by an underlying braid. The distal end of the tip section can have a reinforcing ring on the braid and define an ostium with an angled profile forming an angle perpendicular to the longitudinal axis of the catheter. The ends of the braid can be cut off, or the wire can trace one spiral direction distally and flip proximally at the distal end to trace the other spiral direction. The braid of the expandable distal tip section can accommodate radial expansion, thus the variable PPI and cells are used to balance the allowable expansion of the funnel tip with radial force capability. can have an angle.

The tip and shaft braids can be monolithically formed or joined separately. In some examples, the tip and shaft braid can be made from the same material, or they can be different materials. As an example, the distal wire of the tip braid can be Nitinol or another shape memory superelastic alloy composition and can be heat set to the desired expanded diameter of the tip during manufacture.

In other examples, the tip and shaft braids can have wires of different thicknesses, thereby allowing the distal tip and the shaft to remain aligned while navigating the catheter through bends in the anatomy. There is a hinge effect between them. The hinge may allow the distal tip section to be kept relatively short to reduce its tendency to elongate or shorten under tensile or compressive loads.

Longitudinally, the elastically expanded shape of the tip may be substantially funnel-shaped, flaring radially from the shaft, such that in the lateral plane the tip section is collapsed. It has a circular cross-section in both the delivery configuration and the expanded deployment configuration. In one example, the circular profile of the tip section in the collapsed delivery configuration can define a center coinciding with the longitudinal axis of the elongated body. Alternatively, the circular profile of the tip section in the expanded, deployed configuration may result in the center being radially offset from the longitudinal axis.

A stiffening ring may be disposed around the distal mouth of the expandable distal tip section. At least a portion of the ring can define an ostium plane that forms an acute angle with the longitudinal axis of the catheter when the distal tip section is in the collapsed delivery configuration. This angle may be similar or different when the tip section is deployed in the expanded configuration. In one example, the angle can range from about 30 degrees to about 60 degrees. In another more specific example, the angle can be about 45 degrees,

The stiffening ring can be polymeric, metal, or other suitable material that can add stiffness and shape to the distal end of the tip section. In a preferred example, the stiffening ring is a shape memory alloy such as Nitinol that can be heat set to a desired expanded inner diameter greater than the collapsed inner diameter when the distal tip section is in the expanded deployed configuration. obtain. In another example, the reinforcing ring can be overmolded onto the braid. In a further alternative, the ring may be PVC or other suitable density polymer.

During manufacture, the reinforcing ring can be welded to the distal braid of the tip section. In other examples, brazing, friction welding, adhesives, or other means may be used to attach the reinforcing ring.

To facilitate consistent expansion and collapse of the expandable tip section, the reinforcing ring can have multiple relief features in its circumferential profile. In some designs, the relief feature can be machined into the ring, or the ring can be formed into the mold with the feature. The braided wire of the tip braid can be cut to follow the contour of the relief feature at the distal end of the tip section. Alternatively, the braided wire can be wrapped around the reinforcing ring and the relief feature.

The feature can be, for example, a keyhole shape with parallel sections and a rounded section extending proximally from the distal edge around the stiffening ring. Alternatively, the relief feature may be an axial slot or other geometric shape extending proximally from the distal perimeter of the mouth formed by the stiffening ring. Features may have portions that are parallel to the longitudinal axis or that form an angle with the axis.

The feature can reduce the cross-sectional profile of at least a portion of the tip section. The features can also be axially or longitudinally offset from the oblique mouth plane. This effective reduction of material by the relief features promotes folding along specific planes around the tip. The features can be evenly spaced around the circumference of the ring so that the folding is symmetrical about the longitudinal axis during collapse into the outer sheath. Alternatively, the features can be intermittently spaced apart to advantageously encourage folding along particular planes. Additionally, the relief feature can form an angle with the axis to bias tip section collapse in a particular direction.

Other catheter designs of the present disclosure include a proximal elongated shaft having a proximal end, a distal end, and a tubular shaft braid defining a lumen and a longitudinal axis extending therethrough. can have The shaft may terminate distally in a radiopaque marker band. An expanding distal tip section can be disposed at the distal end of the elongated shaft and can have a support tip braid and a stiffening ring attached to the distal end of the tip braid.

The marker band can be a radiopaque material or can include a radiopaque coating or filler material. The material may be compatible with the material of the shaft braid and tip braid so that the braid ends may be welded or otherwise attached to the marker band, which acts as a joint between sections. In some examples, the proximal end of the support tip braid can be welded to the marker band. In another example, the distal end of the shaft braid can be welded to the marker band. In a further example, welding or adhesives can be used to connect the shaft braid to the tip braid and attach the combined structure to the band.

The distal tip section can have a collapsed delivery configuration and an expanded deployment configuration. The stiffening ring at the distal end of the tip section can have a plurality of relief features or notches equally spaced about the longitudinal axis. The notch can reduce the cross-sectional profile around the reinforcing ring. At least a portion of the stiffening ring may be planar to define an oral plane that forms an acute angle with the axis when the tip section is in the collapsed delivery configuration, the expanded deployment configuration, or both. At least a portion of each of the relief features may be offset from the oral plane so as to extend proximally from the oral plane.

The profile of the distal tip section may be substantially symmetrical about the longitudinal axis when in the collapsed delivery configuration, but may be asymmetrical or offset when in the expanded, deployed configuration. The center of the expanded tip can be radially offset from the center of the catheter shaft.

A polymeric membrane or jacket can be wrapped around the shaft braid and the tip braid. The jackets are placed axially in series and can be selected from materials that are melt-compatible with each other so that adjacent layers help to hold the underlying braid therebetween. Materials can also be selected so that the stiffness of different sections of the catheter can be varied stepwise or continuously. The cooperation between the braid and the polymer jacket allows for a thin-walled yet kink-resistant catheter.

Part or all of the distal tip section can be covered or wrapped with the distal-most tip jacket. The tip jacket can be a very flexible material so as to have the most atraumatic transvascular profile. For example, low durometer Pebax having a hardness ranging from about 42 Shore A to about 72 Shore A can be used. Alternatively, a 62 Shore A or even 42 Shore A tip can be encapsulated by reflowing a Neusoft layer.

The distal-most polymer tip jacket can be trimmed to follow the contours of the reinforcing ring around the ostium of the tip section of the catheter. The distal edge of the tip jacket can coincide with the distal edge of the stiffening ring, including a circumferential gap to follow the contours of the relief features of the ring. Alternatively, the tip jacket can be trimmed to the rounded or oval edge of the beveled tip, but webbed over a notch in the relief feature. A further design may have the tip jacket extending distally beyond the distal edge profile of the stiffening ring as a flexible lip protruding into the ring.

Other aspects of the disclosure will become apparent from a consideration of the following detailed description in conjunction with the accompanying figures. Additional features or steps of manufacture and use may be included as recognized and understood by those skilled in the art.

The above and further aspects of the present invention are further discussed with reference to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in the various drawings. The drawings are not necessarily to scale, the emphasis instead being on illustrating the principles of the invention. The figures depict, by way of illustration only and not by way of limitation, one or more implementations of the device of the present invention. It is expected that one skilled in the art could conceive and combine elements from multiple figures to better suit the needs of the user.
FIG. 3 is a view of the distal portion of a clot retrieval catheter having an expandable tip, in accordance with aspects of the present invention; 2 illustrates a side view of the catheter of FIG. 1, in accordance with aspects of the present invention; FIG. 3 shows a close-up view of the catheter tip section of FIG. 2 in a collapsed delivery configuration, according to aspects of the present invention; FIG. 4 depicts an end view of the catheter tip section of FIG. 3, in accordance with aspects of the present invention; FIG. FIG. 10 illustrates a stiffening ring for a catheter tip section, according to aspects of the present invention; FIG. 3 illustrates the catheter tip section of FIG. 2 in an expanded, deployed configuration, in accordance with aspects of the present invention; 7 is an end view of the tip section of FIG. 6, in accordance with aspects of the present invention; FIG. FIG. 3 is an illustration of a catheter being advanced through a bend in the vasculature, in accordance with aspects of the present invention; 1 illustrates a catheter deployed at a target site, according to aspects of the present invention; FIG. 10 is another example of a distal portion of a clot retrieval catheter, in accordance with aspects of the present invention; 4 depicts another example distal portion of a clot retrieval catheter, in accordance with aspects of the present invention; 4 illustrates the manner in which the stiffening ring and tip jacket may be oriented, in accordance with aspects of the present invention; 4 illustrates the manner in which the stiffening ring and tip jacket may be oriented, in accordance with aspects of the present invention; 4 illustrates the manner in which the stiffening ring and tip jacket may be oriented, in accordance with aspects of the present invention;

Specific embodiments of the invention will now be described in detail with reference to the drawings. The design herein uses a large internal bore and a distal tip section that can self-expand in a substantially funnel-like manner with a diameter larger than that of the guide or sheath into which it is coaxially delivered. for a clot retrieval catheter. The design may have a proximal elongated body for the shaft of the catheter and a distal tip with an expanding braided support structure and an outer polymer jacket to provide atraumatic properties of the tip. can. The tip section can have a stiffening ring at the distal end that serves to add hoop strength and prevent the braid and jacket from collapsing under suction ingestion. The tip design of the catheter is also flexible enough to navigate through highly tortuous regions of the anatomy while still being flexible when collapsed into the delivery structure or displaced within the vessel. It is possible to recover the shape and maintain the inner diameter of the lumen.

Accessing various vessels within a vessel, whether coronary, pulmonary, or cerebrovascular, involves well-known procedural steps and the use of numerous conventional, commercially available accessory products. These products, such as angiographic materials, mechanical thrombectomy devices and stent retrievers, microcatheters, and guidewires, are widely used in laboratories and medical procedures. When these products are used with the device and method of the present invention in the following description, their function and precise construction are not described in detail. Additionally, although these descriptions may relate to thrombectomy treatments in intracranial arteries, the disclosure is equally applicable to other procedures and other body passageways.

Referring to the Figures, FIG. 1 illustrates a clot retrieval catheter 100 of the design disclosed herein. The catheter can have an elongated shaft 110 and a tip section 210 distally attached thereto. The tip section 210 can radially expand to provide better aspiration efficiency and a larger distal port 218 for ingesting occlusive clots. The mouth 218 of the tip section can comprise an angled or slanted distal surface at an angle to the longitudinal axis 111, which presents an angled mouth with a larger area for aspiration and clot uptake. do. Incorporating a stiffening ring 211 at the distal end 214 of the tip section 210 to hold the braid 220 structure of the tip in an expanded funnel shape during aspiration and facilitate wrapping when retracted into the outer sheath. can be done. The catheter may have one or more radiopaque marker bands 116 to identify various transition points and terminations of the device during the procedure.

The braided sections of the shaft and tip can be formed monolithically or in separate sections. In many cases, four or more separate braid sections of different flexibility can be used. It can be appreciated that different braided sections of the tip and shaft braids can have different geometries and weave patterns to achieve the desired properties of that portion of the catheter. Therefore, through selection of physical parameters and materials, different flexibility and stiffness characteristics can be imparted to different sections of catheter 100 to meet clinical requirements.

The elongated shaft may have a backbone comprised of shaft braided sections and surrounded by an axial series of outer body jackets 160 . Similarly, the tip section 210 can have a tip braid 220 surrounded by one or more polymeric tip jackets 180 . The jacket can be made from various medical grade polymers known in the art, such as PTFE, polyether block amide (Pebax®), or nylon.

The braid 220 in the distal tip section 210 may have nitinol wires formed into an expanded freeform with a funnel profile when expanded. Nitinol braided wire, such as the wire of the tip braid, can also be used for the proximal braid 120 of the shaft 110, but the less expensive stainless steel wire can be substituted for lower cost and stiffness in these areas. can also be demonstrated.

As used herein, the terms "braided section," "braid," and like terms are used collectively to describe the support structure of the catheter shaft and tip. This type of catheter construction is generally known in the art. The term can refer to segments within a single monolithic braid having different physical properties (PIC count, braid angle, etc.) and/or configurations, and does not necessarily imply two separate structures attached together. Alternatively, the term may refer to a collection of separate sections knitted together.

Marker bands 116 may be positioned at or on the distal end of shaft 110 and the proximal end of tip section 210 . The marker band can be platinum, gold, and/or another metallic color, or alternatively can be coated with a compound that provides substantial radiopacity. To minimize the impact on shaft flexibility, the band may be kept relatively short in length, eg 0.3-1.0 mm. Bands 116 can be crimped in place or slid over a mandrel and later glued to the ends of the braided sections. In some examples, the band 116 can also serve as a joint between the braid of the tip section 210 and the shaft 110, allowing each braid section to be separately cut into any of a number of desired lengths. Allows for rapid manufacturing and banding together. If the catheter length is 1350 mm, which is typical of many designs, the tip section 210 may be about 100 mm long, with the 1250 mm shaft 110 terminating in a proximal luer. Using a specific metal such as platinum for the sleeve of the marker band 116 (which can be welded to both stainless steel and nitinol) provides a more robust joint instead of using adhesives or other means. can be created.

The lumen of the catheter shaft can be sized such that the catheter 100 is generally sized and compatible with readily available guide sheaths. A low-friction inner liner may be disposed under the blade 120 to facilitate use of the lumen for delivery of ancillary devices, injection of contrast media, and direct distal aspiration to the clot plane. . Preferred liner materials can be fluoropolymers such as polytetrafluoroethylene (PTFE or TFE), ethylene-chlorofluoroethylene (ECTFE), fluorinated ethylene propylene (FEP), polyvinyl fluoride (PVF), or similar materials. . Depending on the material chosen, the liner may be stretched to alter the orientation of the liner material (e.g., if the liner material has fibers, the imposed stretch may change the nominally isotropic sleeve to a more anisotropic longitudinal composition). material), and the wall thickness can be reduced if desired.

Body jacket 160 and tip jacket 180 can be butted together to form a continuous and smooth outer surface of the catheter shaft. The polymer jacket can be reflowed or laminated in place along the length of elongated shaft 110 and tip section 210 . The applied heat can allow the outer polymer to fill the interstitial sites between the braids. This flow may also help to axially fix the jacket so that it cannot slide distally.

These outer jackets, in combination with the braided construction, have higher column stiffness (due to durometer hardness, flexural modulus, etc.), transitioning the proximal portion of the catheter to the distal portion having more lateral flexibility. It can have varying durometer hardness to create the part. In some examples, the body jacket can have a hardness ranging from about 25 to about 72 Shore D. The tip jacket 180 or jackets can have a distal-most jacket with the least stiffness for the least traumatic cross-vessel profile.

FIG. 2 shows a profile view of the distal portion of catheter 100 of FIG. As disclosed, a distal marker band 116 of about 0.8 mm in length is placed in close proximity to the polymer tip jacket 180 to provide radiopacity near the distal end 214 of the tip section 210. can be included in the Marker band 116 may be platinum or another suitable noble metal and may be crimped over, under, or between the assembly of braids 120, 220 of shaft 110 and tip section 210. As shown in FIG. The band 116 can also be located at or near the distal end 114 of the shaft and at least 5 mm and up to 10 mm or more from the distal end 214 of the tip section 210 . Alternatively, or in addition, the stiffening ring 211 of the distal tip section 210 can be constructed of a radiopaque material to illuminate the final distal end of the device when interacting with the clot; or can be coated or embedded with such materials.

Catheter shaft 110 can have one or more axial spines (not shown) that extend with shaft braid 120 along longitudinal axis 111 . The spine or spines 117 can resist tensile elongation and contribute to the pushing properties of the shaft. This is particularly beneficial when the spine 110 is subjected to a large pulling force when a large hard clot lodges at the distal end of the catheter and the catheter is pulled into the large outer sheath for removal from the vessel. The spine can be positioned under the braid, passed between the stitches of the braid, resting on the outer diameter of the braid, or a combination thereof. The spine can be composed of metal, polymer, or composite strands such as Kevlar. In other examples, the spine may be a thread or other structure capable of supporting tensile loads but not compressive loads. Some preferred examples may utilize liquid crystal polymers (LCPs), such as Technora, which are easy to process and provide high tensile strength without sacrificing any lateral flexibility.

As the catheter 100 is delivered to the target site or pulled back into the access catheter/outer sheath in the collapsed delivery configuration shown, the tip section 210 compresses the braid 220 around the circumference of the stiffening ring 211. can be wrapped radially downward to fold at the relief feature 224 of the . For access catheters, the tip section 210 can have a collapsed inner diameter 215 that is the same as or approximately the same as the inner diameter 115 of the elongate shaft 110 .

As shown in FIGS. 1 and 2, distal end 214 of tip section 210 can have an angled surface that is angled at an angle 217 with respect to longitudinal axis 111 . The beveled surface can increase aspiration efficiency and present a larger mouth area for improved clot uptake, resulting in improved recoil when compared to catheters with non-beveled tips. Perfusion and recycling results can result. As such, the beveled tip can potentially reduce the number of passes required for a successful procedure or reduce additional complications associated with the introduction of mechanical clot retrieval devices.

When tip section 210 is in its collapsed state, the angled distal face of annular mouth 218 of tip section 210 may lie on angled plane 213 at acute angle 217 with longitudinal axis 111 . Plane 213 may lie at an angle of at least about 10 degrees to at least 60 degrees with respect to the axis. For a more atraumatic profile during navigation, preferred angle 217 may range from about 30 degrees to 60 degrees, or more specifically about 45 degrees.

The inner diameter 115 of the catheter shaft 110 and the collapsed inner diameter 215 of the expandable tip section 210 are appropriately sized to fit any widely employed outer guide and/or sheath of choice. can be determined and scaled. The cross-section of the tip section and shaft can be approximately symmetrical when collapsed, for example, a 5 Fr catheter targeting a vessel with a diameter of about 2.0 mm has a shaft/tip section of about 0.054 inches. It can have an inner diameter 115,215. Similarly, a 6Fr catheter targeting vessels of about 2.3-3.4 mm in diameter can have a shaft/tip inner diameter 115, 215 of about 0.068-0.074 inches. Larger nominal 8Fr catheters for less distant clots may have shaft/tip inner diameters 115, 215 of about 0.082-0.095 inches. In most situations, the practical upper design limit for collapsed tip diameter 215 is limited by friction and other delivery forces as they traverse within the outer guide or sheath.

The stiffening ring can have various shapes that determine the profile of the distal end 214 of the tip section 210, as seen in the closer view of the collapsed tip illustrated in FIG. Ring 211 may be affixed around the distal edge of tip braid 220 through welding or brazing. In one example, the stiffening ring 211 can be a nitinol member that grips the underlying braid tightly, and the distal portion of the tip section when changing to the larger diameter deployed state outside the guide or sheath. is set to a free shape that elastically expands in the radial direction. Alternatively, ring 211 can be a polymeric material and can be overmolded, injection molded, or sprayed or dipped onto the braided layer using masking.

The length and profile of tip section 210, which tapers in a substantially funnel shape from distal end 214 when expanded, can be adjusted through the design of the pattern of tip braid 220 and reinforcing ring 211. . As noted above, in addition to or instead of ring elements, the wires of braid 220 have shape memory properties and can be heat set to a desired designed elastic free shape. For example, a shorter funnel section can provide the advantage of good hoop stiffness and flexibility through having a shorter lever distance to hinge the elongated shaft 110 . Additionally, a shorter funnel can be tailored to minimize stretching and deformation of the outer polymeric tip jacket 180 more distally. Alternatively, a longer funnel with a shallower taper may interact better with the clot and allow for more gradual clot compression over the length of the tip, thus reducing the risk of stagnation. .

The reinforcing ring 211 can be formed as a single piece of uniform thickness or can vary in thickness in certain sections. In FIG. 3, ring 211 has no webs or ligaments between relief features 224 as these sections make up the majority of the mouth circumference and can provide the greatest radial force to resist suction forces. can have a slightly larger thickness 221 for curing. Ring 211 may transition to a lesser thickness 222 in the area of relief features 224 to further bias tip folding and collapsing along these planes. The tip jacket 180 can also be trimmed to follow the contour of the stiffening ring 211 (around the release feature 224) so as not to add additional stiffness in these areas while maintaining symmetry in folding. including proximal trimming).

Relief feature 224 may be a keyhole-shaped projection that extends proximally from the distal perimeter of stiffening ring 211 at catheter port 218 . The keyhole shape may have two parallel sections 225 extending from the angled annular portion of ring 211 and terminating in a rounded section 226 that acts as a stress reliever and articulation enabler for the ring structure. The keyhole relief feature 224 hinges about the rounded section 226 to allow the ring to be "opened" and "closed", allowing the distal tip 210 to be repeatedly expanded and collapsed without breaking. Become. The interrupting nature of the relief features 224 around the mouth 218 also serves as a flange or key during and after manufacture to help locate and secure the reinforcing ring 211 to the underlying braid 220. means

FIG. 4 depicts an end view of distal tip section 210 in a collapsed delivery configuration. The collapsed inner diameter 215 of the tip section can be approximately equal to the inner diameter 115 of the shaft 110 when constrained within the outer sheath. Depending on the final design profile of the stiffening ring 211, the tip section and shaft can be concentric about a common center 117 when the tip is collapsed, or can be offset. Annular mouth 218 may be an ellipse lying on an oblique plane inclined from longitudinal axis 111 .

As seen in the perspective view of stiffening ring 211 in FIG. 5, four relief features 224 spaced at 90 degree intervals allow tip section 210 to maintain the inner diameter of mouth 218 for use with an attached device, while still allowing tip section 210 to sag. Helps wrap evenly and symmetrically. Note that a greater or lesser number of relief features can be envisaged. The features can be evenly spaced about the longitudinal axis to promote symmetrical folding of the tip section. For example, six relief features at 30 degree intervals may be employed. Alternatively, in some other examples, the reinforcing ring 211 may incorporate an odd number or relief features, or features that are aligned with the mouth to bias folding in a particular direction in the plane of the mouth. It can be asymmetrically spaced around.

The keyhole-shaped relief features 224 of this example of the stiffening ring 211 may each have two parallel sections 225 proximally joined by a rounded section 226 . Each relief feature can thus function as an opening to allow radial expansion of the tip section. As illustrated in FIG. 6, mouth 218 of tip section 210 can expand from a collapsed diameter 215 to a larger inner diameter 230 in the expanded, deployed configuration. The angled distal end can define an enlarged oral plane 228 that is angled at an acute angle 219 with respect to the longitudinal axis 111 . The sloping profile allows a larger entry area to facilitate entrapment of a firm clot, allows more gradual compression of the clot over the longer tip length, and allows the clot to be fully entrapped and catheterized. improve the likelihood that it can be sucked through the shaft of the

One or both of the reinforcement ring 211 and the wires of the tip braid 220 may be made of Nitinol or another shape memory superstructure so that the solid phase transition may be designed to dictate the constrained delivery and unconstrained deployment diameter of the tip. It can be an elastic alloy. The tip braid 220 can be trimmed to follow the contours of the stiffening ring 211, which overhangs the end of the braided wire such that the tip section is funneled out when allowed to expand. can be welded or brazed to Stiffening ring 211 can be heat set into a free shape with a larger expanded inner diameter 230 when catheter 100 is deployed from the outer sheath. When collapsed, the stiffening ring 211 and tip braid 220 can have an inner diameter that approximates the inner diameter of the catheter bore when constrained. Alternatively, the wires of the braid can also be drawn-fill tube (DFT) shape memory alloy with a platinum core so that the braid is visible under fluoroscopy.

A further advantage of using a superelastic material for the braided wire and using a stiffening ring as the primary structural support element of the tip section 210 is that it can be used without sacrificing performance characteristics such as flexibility or crush strength. , the catheter wall can be relatively thin, thus adding stiffness to the tortuous bends of the tip section 210 . Thinner walls allow a larger effective bore size for suction.

Radiopaque marker bands may be included at different axial points along the length of catheter 100 for fluoroscopic visualization during the procedure. In the illustrated example, the marker band 116 can illuminate the location of the distal end 114 of the shaft 110 to give the attending physician an indication of where the expandable volume of the catheter begins. The band shown has a relatively short length of about 0.025-0.030 inches and a thin wall thickness (about 0.0005 inches) to minimize impact on catheter flexibility and outer diameter. can be platinum strips or other precious metals with

As shown in FIGS. 6 and 7 , when tip section 210 is expanded, the central axis and most of the tip can be offset from nominal longitudinal axis 111 of shaft 110 . Thus, the center 232 of the tip section can move radially away from being coincident with the shaft center 117 and become more asymmetric as the tip expands. Having an offset shape and an angled distal ostium 218 allows for increased lateral flexibility so that the tip section 210 better tracks the vessel wall as it is advanced to the target site. , can be deflected. FIG. 8 shows that the beveled shape of the tip section 210 can be deflected away from tight bends when tracking within the vasculature 10, and the notch extending proximally of the relief feature 224. allow the tip section to flex in response in the presence of local forces. In many situations, when at the target site, the catheter is also manipulated and torqued so that the beveled mouth 218 of the tip section 210 is in-plane with the clot plane for better clot management at the interface. An increased access area can be provided.

The expandable tip section 210 can be designed to be advanced through the expanded vasculature. In these examples, the expandable tip can have a maximum inner diameter in the expanded state approximately equal to the diameter of the target vessel immediately proximal to the target clot. In most instances, the expanded funnel tip can be sized to have an inner diameter that is larger than the inner diameter of the outer sheath and/or guide through which it is delivered.

During delivery, the collapsed inner diameter 215 of the tip section can be approximately the same as the nominal diameter 115 of the catheter shaft section. Once expanded, the expanded inner diameter 230 of the tip section 210 can scale linearly with the nominal diameter 115 of the vessel being accessed. For example, a catheter having an inner diameter in the shaft of approximately 0.070 inches can have a tip section 210 with a maximum inner diameter 230 of approximately 0.090 inches in the expanded, deployed configuration. Similarly, catheters having other common size shafts, such as 5 Fr to 9 Fr, are envisioned with flared tip diameters 230 scaling accordingly for an overall range of about 0.075 to 0.200 inches. can be

When using the catheter 100 of the present disclosure to remove an occlusion from a body vessel, the catheter with the collapsed tip passes through the outer catheter or sheath 30, as depicted in FIG. A proximal location can be advanced. The sheath 30 is typically positioned as close as possible to the occlusive clot, although the location may depend on the target vessel size and the relative tortuosity of the vasculature required to reach it. For example, in the case of middle cerebral artery occlusion, the outer catheter can be positioned in the internal carotid artery proximal to the carotid siphon. For example, if the target occlusion is in an M1 vessel, a typical guide or outer sheath would need to be maintained in a position well proximal to these vessel diameters and the aspiration catheter 100 advanced independently. deaf.

As shown, the guide sheath 30 is anchored well upstream of the occlusive clot and the catheter 100 can be advanced from the distal end 32 of the guide sheath and deployed to an expanded condition. If pure suction proves insufficient to dislodge the clot, the microcatheter 50 can be used to deploy a stentriever or other device known in the art. The combination of a stent leaver and efficient aspiration through an enlarged beveled tip section can work together to increase the likelihood of successful one time clot 40 removal.

As the clot is dislodged from the vessel wall, it can be progressively compressed through the funnel shape of the expandable tip of the catheter and through the lumen into a canister or syringe. Since the stiffening ring provides support against tip collapse, a more flexible braid can be used to further allow for localized radial expansion. Instead of withdrawing the stentriever from a stationary lumen, the catheter 100 also directs the aspiration vacuum toward the clot plane while withdrawing in conjunction with the stentriever to hold the composite clot (consisting of the fractured region and the fibrin-rich region) together. can prevent embolism. In the case of particularly hard clots, this further expansion of the tip section can protect and retract the clogged clot while the catheter itself is being withdrawn.

A contrast agent can be injected to determine the degree to which the vessel is patent. If desired, the clot retrieval device can be rinsed with saline and gently washed before being reloaded onto the microcatheter for an additional pass.

Another alternative design for the distal tip section 210 of a catheter according to the present disclosure is illustrated in FIG. An angled mouth 218 is defined by the perimeter of reinforcing ring 211 having two relief features 224 spaced 180 degrees apart with an enhanced rounded section 226 . Relief feature 224 may extend proximally from mouth 218 such that at least a portion is offset from the angled plane of the bevel. A smaller number of relief features can increase the overall stiffness and available hoop strength of the reinforcing ring 211 . This allows for use with less dense tip braids 220 and can provide greater expansion capacity.

Further, the configuration having two relief features 211 diagonally opposed as shown defines a bending surface of the tip section 210 passing through the two features. Alternatively, additional relief features can be incorporated, including other geometric shapes that define additional planes.

The wires of braid 220 of tip section 210 may be cut and trimmed to the desired profile of reinforcing ring 211 around distal port 218 . In this way, the braid can resemble the ends of a stent at its free ends, making it highly flexible and easy to manufacture. Alternatively, the wires of the underlying braid may be wound in one direction toward the distal end 214 of the tip section. Upon reaching the distal end, the wire can be reversed and wrapped proximally in the opposite direction. As a result, the inverted ends are also more atraumatic with additional manufacturing costs. In this example, the inverted ends of the braid can also be wrapped around the reinforcing ring 211 to improve the strength of the joint.

FIG. 11 illustrates a catheter distal tip section 210 design in which the stiffening ring 211 has relief features 224 in the form of a series of axial slots 227 symmetrical about the longitudinal axis 111 . Axial slot 227 may be a wide arcuate loop extending proximally from ramp plane 213 toward marker band 116 and surrounding tip braid 220 therein. While there are many cases where axial slots 227 or other relief features can be substantially parallel to longitudinal axis 111, in other examples they are parallel sections, or angled with respect to the axis. , or have a spiraling slot centerline. Using slots for relief features can provide a more simplified manufacturing process compared to keyholes or other irregular geometry options.

The distal-most tip jacket 180 can be trimmed to follow the contours of the reinforcing ring 211 and relief features, or extend a longitudinal distance distally to protrude beyond the distal end of the ring. can be done. In the example shown in FIG. 11 , the tip jacket extends over the perimeter of the stiffening ring 211 in the region of the axial slot 227 and the planar shape of the ramp 218 at the distal end 214 of the tip section 210 . give rise to a surface of In some examples, the longitudinal distance of protrusions can range from about 0.1 mm to about 1.0 mm. In a more specific example, this longitudinal distance can range from 0.5 mm to about 0.8 mm.

The tip jacket 180 can also be the most flexible jacket used on a catheter, covering most of the distal length of about 90 mm. The additional integrity provided by the reinforcing ring 211 allows the implementation of increasingly flexible jacket materials. Generally, a hardness in the range of about 42 Shore A to about 72 Shore A may be preferred. In one or more specific examples, a Neusoft jacket having a hardness of approximately 62 Shore A can be reflowed to form the tip jacket 180 . Alternatively, a more flexible Neusoft layer of about 42 Shore A can be used.

Cross-sections demonstrating various examples of layered layouts of the reinforcing ring 211, the tip jacket 180, and the tip braid 220 of the distal tip section 210 are shown in Figures 12a-12c. Jacket 180 may be applied and adhered to the braid and ring through dip coating, reflow, lamination, or other suitable method. In the example shown in FIG. 12 a , the reinforcement ring 211 structure extends radially outward and above braid 220 , which is wrapped by tip jacket 180 . This layout allows the reinforcing ring to protect the distal jacket from abrasion or tearing, especially if, for example, a softer, weaker jacket is utilized. The edges of the stiffening ring may have radii or chamfers to protect the traversed vessel bed.

The alternative shown in Figure 12b can be used when choosing a slightly stiffer, more durable material for the jacket. A jacketed braid 220 may be positioned radially outward and adhered to the outer surface of the reinforcing ring 211 . In this configuration, the reinforcing ring is used to "push" the braid and jacket material outward as the tip section 210 is expanded. Similarly, the stiffening ring will "pull" the braid and jacket material inward when the tip section is collapsed within the outer sheath.

In a further example, an arrangement in which the braid 220 is sandwiched by the reinforcing ring 211 and the outer tip jacket 180 completely envelops both the braid wire and the reinforcing ring is depicted in Figure 12c. To form this structure, a thin inner jacket layer is disposed over a flared mandrel and the mandrel is closely loaded into the distal end of the braid/reinforcement ring combination, leaving the tip section to a radius. direction can be extended. A thin elastic outer polymer layer of the tip jacket extrusion can be screwed or stretched onto the flared mandrel and extruded over the flared section to expand the small extruded material. The combined inner and outer layers of tip jacket 180 can then be reflowed in place and the flared mandrel removed from the catheter assembly.

By sandwiching the braid and having the jacket material envelop all of the underlying assembly, the configuration of Figure 12c can provide very uniform 'push' and 'pull' forces acting on the tip section. Additionally, a completely homogeneous jacket edge is formed at the distal end 214 of the tip section 210 .

The invention is not necessarily limited to the examples described and may vary in configuration and details. The terms "distal" and "proximal" are used throughout the foregoing description and are intended to refer to position and orientation relative to the treating physician. As such, "distal" or "distal" refers to a location distal to or in a direction away from the physician. Similarly, "proximal" or "proximal" refers to a location near or toward the physician. Further, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates.

As used herein, the term “about” or “approximately” to any numerical value or range of numerical values means that a portion of a component or collection of components is the intended value described herein. It indicates the preferred dimensional tolerances that allow it to function as intended. More specifically, "about" or "approximately" can refer to a range of values ±20% of the recited value, for example, "about 90%" refers to a range of values from 71% to 99%. obtain.

In describing the exemplary embodiments, terminology is employed for the sake of clarity. As a result, not all possible combinations have been enumerated, and such variations will often be apparent to those skilled in the art and are intended to fall within the scope of the following claims. . Each term is intended to have its broadest meaning understood by a person skilled in the art, and all techniques that act in a similar manner to accomplish a similar purpose without departing from the scope and spirit of the present invention. are intended to include equivalents. It should also be understood that reference to one or more method steps does not exclude the presence of additional method steps or intervening method steps between those steps that are explicitly identified. Similarly, some steps of the method may be performed in a different order than that set forth herein without departing from the scope of the disclosed technology.

[Mode of implementation]
(1) A catheter,
a proximal elongate shaft including a longitudinal axis, a distal end, a lumen, and a shaft braid;
an expandable distal tip section at the distal end of the elongate shaft, the tip section comprising a collapsed delivery configuration, an expanded deployment configuration, a tip braid, and an angled profile and stiffening; an expandable distal tip section including a distal port including a perimeter defined by the ring;
The catheter of claim 1, wherein the stiffening ring includes a plurality of relief features equally spaced about the longitudinal axis.
(2) The catheter of clause 1, wherein the distal tip section further comprises a substantially circular cross-section in both the collapsed delivery configuration and the expanded deployment configuration.
(3) The catheter of claim 1, wherein the stiffening ring is welded to the tip braid of the distal tip section.
4. The catheter of claim 1, wherein said stiffening ring is overmolded onto said tip braid (220) of said distal tip section.
Aspect 5. The catheter of aspect 1, wherein the stiffening ring comprises a shape memory alloy.

Embodiment 5, wherein said stiffening ring is heat set to include an expanded inner diameter that is greater than a collapsed inner diameter when said distal tip section is in said expanded deployed configuration. The catheter described in .
(7) at least a portion of the tip braid is heat set to include an expanded inner diameter greater than a collapsed inner diameter when the distal tip section is in the expanded deployed configuration; A catheter according to claim 1.
Aspect 8. The catheter of aspect 1, wherein the reinforcing ring comprises a polymer composition.
9. The catheter of claim 1, wherein the tip braid is cut to follow the contour of the relief feature at the distal end of the tip section.
(10) said distal port defines a plane passing through at least a portion of said stiffening ring, said plane being aligned relative to said longitudinal axis when said tip section is in said collapsed delivery configuration; 2. The catheter of embodiment 1, forming an acute angle.

(11) The catheter of embodiment 10, wherein said angle is between about 30 degrees and about 60 degrees.
Clause 12. The catheter of clause 10, wherein at least a portion of the relief feature of the stiffening ring is offset proximally from the plane.
Clause 13. The catheter of clause 1, wherein the relief feature reduces the cross-sectional profile of at least a portion of the tip section.
Aspect 14. The catheter of aspect 1, wherein the relief feature comprises a keyhole shape having parallel and rounded sections.
Clause 15. The catheter of clause 1, wherein the relief feature comprises an axial slot extending proximally from a distal perimeter of the distal port.

(16) A catheter,
a proximal elongated shaft comprising a longitudinal axis, a distal end, a lumen, shaft braid, and a marker band at the distal end of the shaft;
an expandable distal tip section connected to the distal end of the elongate shaft, the tip section comprising a collapsed delivery configuration, an expanded deployment configuration, a support tip braid, and the an expandable distal tip section including a reinforcing ring attached to the distal end of the tip braid;
a polymer tip jacket disposed around the tip section;
at least a portion of the stiffening ring defines an oral plane that forms an acute angle with the longitudinal axis when the tip section is in the collapsed delivery configuration;
The catheter of claim 1, wherein the stiffening ring includes a plurality of relief features equally spaced about the longitudinal axis, at least a portion of each of the relief features offset proximally from the oral plane.
17. The catheter of claim 16, wherein a distal edge of said polymeric tip jacket follows the contour of said stiffening ring.
18. The catheter of claim 16, wherein at least a portion of the polymeric tip jacket extends distally beyond the contour of the stiffening ring.
19. The catheter of claim 16, wherein the polymeric tip jacket has a hardness ranging from about 42 Shore A to about 72 Shore A.
20. The catheter of claim 16, wherein the proximal end of the support tip braid is welded to the marker band.

Claims (20)

a catheter,
a proximal elongate shaft including a longitudinal axis, a distal end, a lumen, and a shaft braid;
an expandable distal tip section at the distal end of the elongate shaft, the tip section comprising a collapsed delivery configuration, an expanded deployment configuration, a tip braid, and an angled profile and stiffening; an expandable distal tip section including a distal port including a perimeter defined by the ring;
The catheter of claim 1, wherein the stiffening ring includes a plurality of relief features equally spaced about the longitudinal axis. A catheter of claim 1, wherein the distal tip section further comprises a substantially circular cross-section in both the collapsed delivery configuration and the expanded deployment configuration. A catheter of claim 1, wherein the reinforcing ring is welded to the tip braid of the distal tip section. A catheter of claim 1, wherein the reinforcing ring is overmolded onto the tip braid (220) of the distal tip section. A catheter of claim 1, wherein the stiffening ring comprises a shape memory alloy. 6. The reinforcing ring of claim 5, wherein the stiffening ring is heat set to include an expanded inner diameter that is greater than a collapsed inner diameter when the distal tip section is in the expanded deployed configuration. catheter. 10. At least a portion of said tip braid is heat set to include an expanded inner diameter greater than a collapsed inner diameter when said distal tip section is in said expanded deployed configuration. 1. The catheter according to 1. A catheter of claim 1, wherein the reinforcing ring comprises a polymer composition. A catheter of claim 1, wherein the tip braid is cut to follow the contour of the relief feature at the distal end of the tip section. The distal port defines a plane passing through at least a portion of the stiffening ring, the plane forming an acute angle with the longitudinal axis when the tip section is in the collapsed delivery configuration. The catheter of claim 1, wherein: A catheter of claim 10, wherein the angle is from about 30 degrees to about 60 degrees. 11. The catheter of claim 10, wherein at least a portion of the relief features of the stiffening ring are offset proximally from the plane. A catheter of claim 1, wherein the relief feature reduces the cross-sectional profile of at least a portion of the tip section. A catheter of claim 1, wherein the relief feature comprises a keyhole shape having parallel and rounded sections. A catheter of claim 1, wherein the relief feature comprises an axial slot extending proximally from a distal perimeter of the distal port. a catheter,
a proximal elongated shaft comprising a longitudinal axis, a distal end, a lumen, shaft braid, and a marker band at the distal end of the shaft;
an expandable distal tip section connected to the distal end of the elongate shaft, the tip section comprising a collapsed delivery configuration, an expanded deployment configuration, a support tip braid, and the an expandable distal tip section including a reinforcing ring attached to the distal end of the tip braid;
a polymer tip jacket disposed around the tip section;
at least a portion of the stiffening ring defines an oral plane that forms an acute angle with the longitudinal axis when the tip section is in the collapsed delivery configuration;
The catheter of claim 1, wherein the stiffening ring includes a plurality of relief features equally spaced about the longitudinal axis, at least a portion of each of the relief features offset proximally from the oral plane. 17. The catheter of claim 16, wherein the distal edge of the polymeric tip jacket follows the contour of the stiffening ring. 17. The catheter of claim 16, wherein at least a portion of the polymeric tip jacket extends distally beyond the contour of the stiffening ring. 17. The catheter of claim 16, wherein the polymeric tip jacket has a hardness ranging from about 42 Shore A to about 72 Shore A. 17. The catheter of claim 16, wherein the proximal end of the support tip braid is welded to the marker band.

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